Luxman LV-105u (1984)
A hybrid integrated amplifier with two glowing 6CG7 twin-triodes in the driver stage and MOS-FETs doing the heavy lifting. The tubes are lit on purpose.
Overview
The Luxman LV-105u is a hybrid integrated amplifier introduced in 1984, with tubes and transistors in a single chassis. Luxman's own advertising of the period called it "reproduction accuracy not previously attainable using either technology alone" - a claim every hybrid maker of the era made, but this amp has an unusual circuit topology to back it up. An FET handles the first stage, a 3-pole tube takes the pre-driver stage, and MOS-FETs deliver the last stage. It is voltage-driven from input to output, and built around two 6CG7A twin-triode vacuum tubes in the driver stage. An integrated pre-heating function illuminates those tubes. That is a bit of theater, but it shows you what's inside.
Power output is where the documentation gets slippery. The page summary rates the amp at 100 watts per channel into 8 ohms (20Hz - 20kHz, both channels driven) with no more than 0.02% THD. One cited source lists 150W/ch into 8 ohms, a figure that more plausibly belongs to the US-export LV-105. The Audio Database entry is more granular: 105W + 105W into 6 ohms and 80W + 80W into 8 ohms, both across 20Hz to 20kHz. Treat the 100W/8-ohm figure as the working number and the 150W claim with suspicion. The Audio Database quotes harmonic distortion at 0.008% at 6 ohms, 1kHz. That is far better than the 0.02% ceiling in the page summary, and it reflects the voltage-controlled amplifier design Luxman used across all stages to eliminate current distortion.
The design philosophy is spelled out in Audio (October 1990, p.332). It noted that Luxman's integrated amplifiers of this type employed voltage-driven amplification for optimum dynamic performance with negligible transient intermodulation or slew-induced distortion. They were backed by high-energy power supplies with substantial filter capacitance, to deliver the steady-state and dynamic power needed for demanding musical transients.
Key Features
Tube/MOS-FET Hybrid Topology
The LV-105u has a three-stage signal path: an FET input stage, a 3-pole tube pre-driver built around the two 6CG7A twin-triodes, and a MOS-FET output stage. Luxman's stated rationale was that voltage-controlled amplification at every stage eliminates current distortion. The tubes contribute voltage gain and their characteristic harmonic profile, while the MOSFETs supply the current the speakers demand. The 6CG7 tubes are visible through the chassis and lit by the pre-heating circuit, which is either charming or gimmicky depending on your disposition. Owners who love the amp tend to describe it as combining tube warmth with solid-state power. Owners who don't describe a clean, detailed solid-state character that lacks tube warmth entirely.
S.T.A.R. Circuit and Linear-Drive Power Supply
The "LV" designation reportedly stands for "Linear Voltage," a reference to the linear-drive power supply design. The power supply uses a large transformer with a core reportedly 50% thicker than usual. Luxman's S.T.A.R. circuit supplies power directly to each amplification stage without sharing feed and ground lines, so the signal-path ground stays independent all the way to each stage's reference point. The LV-105u also applies the S.T.A.R. approach to the signal path itself. Marketing framing aside, the topology is the reason the amp runs quiet. Signal-to-noise is quoted at 105dB in the page summary, and the Audio Database gives 110dB for CD/tuner/line inputs, 90dB for phono MM, and 70dB for phono MC.
Dual Phono Stages with MM/MC Switching
Two phono inputs are provided, both MM, with a switchable MM/MC option on the phono preamp - an MC/MM high-gain equalizer amplifier built around a low-noise FET. Input sensitivity is 2.0mV for MM and 150μV for MC, with input impedance of 47k ohms for MM and 100 ohms for MC. Line-level inputs (CD, tuner, line) are rated at 150mV into 47k ohms. Frequency response for the phono section is quoted at 20Hz - 20kHz ±0.3dB. The line section reaches from 1Hz to 200kHz at −3dB per the Audio Database, though the page summary gives a conflicting 5Hz - 100kHz (+0/−3dB). The AV inputs are a separate story at 10Hz to 6MHz at −3dB, because this amp was built for the video era.
CD Straight-Through and Video Buffer
The LV-105u includes a CD straight-through function that bypasses part of the circuit and routes the CD signal to the power amplifier over the shortest possible path. That was a genuine convenience in 1984, when CD players were new and their output levels were still being standardized. There's also a built-in video buffer amplifier that can reliably send up to 6MHz video signals to a monitor or VCR, and two AV terminals, one of which can be switched between front and rear. This amp was designed for a living-room stack that included a VCR, not just a turntable.
Tone Controls, Speaker Selection, and Ergonomics
Tone controls offer ±10dB at 50Hz for bass and ±10dB at 20kHz for treble, with a defeat switch. Speaker selection covers A, B, or A+B. A stereo/mono mode switch and a loudness control round out the front panel, and there's a switched AC outlet on the back. The voltage selector is a four-position mechanical switch (100/120/220/240V) rather than auto-switching, and the amp uses a standard IEC-style AC cord. Luxman's documentation warns that line voltage is preset and should not be changed in North America unless the local voltage is known to be correct. Heed that before you flip the selector on a unit of unknown provenance.
Historical Context
The LV-105u arrived in 1984, positioned in Luxman's "u" series above the LV-103u and below the LV-109u, alongside the LV-12u. It was an evolution of the LV-105 concept, "improved while taking over the concept of the LV 105," as the Audio Database puts it, and like its predecessor it used the tube/MOS-FET hybrid configuration. The "u" suffix distinguishes it from the US-export LV-105, which appears to have had higher power output (150W/ch).
Market positioning and pricing are murky. One source describes the LV-105u as a budget-oriented integrated amplifier aimed at the Australian market. Another suggests it may have been built for the Japanese domestic market or a specific export region. Original pricing is just as conflicted: approximately $695 in the US or ¥168,000 in Japan according to one source, versus ¥129,000 from the Audio Database. The Audio Database also lists a release date of October 1986, which conflicts with the 1984 introduction date in the page heading. Production end year is not confirmed. What is clear is that the amp was made in Japan by Lux Corporation, Tokyo, and sold under both the Luxman and Alpine/Luxman names depending on market.
Reception and the Used Market
Owner sentiment runs warm. One long-term owner reported after 25 years that the amp still sounds great and was "a steal at the price"; another called it one of the best integrated amps ever made with high-efficiency speakers. The criticisms are consistent too: a clean, detailed solid-state character lacking tube warmth, and a slight brightness that can turn harsh with poor recordings. An audioreview.com owner complained of relatively poor bass performance and a muddled midrange at higher listening levels. Evidently 100 watts into 8 ohms is not the same thing as iron-fisted current delivery, whatever the MOSFETs claim. Aggregate owner rating sits at 4.4 out of 5 across 10 reviews. There's also an anecdotal failure report of an amp that no longer clicks on and won't power up, though the tubes still light. That kind of symptom points to a protection relay or supply fault rather than the tubes themselves.
On the used market, prices have firmed up. A Reverb listing from November 2021 shows a LUXMAN LV105u selling for $600, and a Portuguese classified listed one at €500 in July 2017. A current eBay listing for a "Vintage Luxman LV-105u Hybrid Tube/MOSFET Integrated Amplifier" carries a $1,100 asking price, though no date is attached to that figure. The amp's complexity - tubes, MOSFETs, a multi-stage supply - means service is not a DIY proposition for the inexperienced, and documentation on maintenance procedures is thin.
eBay Listings
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.
Related Models
- Luxman MS-11 (1974)
- Luxman 5L15
- Luxman 5T-50 (1977)
- Luxman C-03 (1978)
- Luxman C-9II (1979)
- Eico 3150 (1967)
- Fisher CUSTOM-ELECTRA-I (K-14/K-15) (1957)
- Fisher CUSTOM-ELECTRA IV (E33/E44) (1960)
- Akai AM-2400 (1978)
- Akai AM-2600 (1977)